type of last arg of objc_assign_ivar is  ptrdiff_t. 
// rdar://9362887


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@130956 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGObjCMac.cpp b/lib/CodeGen/CGObjCMac.cpp
index 0675f0d..6473bb2 100644
--- a/lib/CodeGen/CGObjCMac.cpp
+++ b/lib/CodeGen/CGObjCMac.cpp
@@ -324,7 +324,11 @@
     // id objc_assign_ivar(id, id *, ptrdiff_t)
     std::vector<const llvm::Type*> Args(1, ObjectPtrTy);
     Args.push_back(ObjectPtrTy->getPointerTo());
-    Args.push_back(LongTy);
+    const llvm::Type *PtrDiffTy =
+      CGM.getTypes().ConvertType(
+        CGM.getContext().getPointerDiffType()->getCanonicalTypeUnqualified());
+
+    Args.push_back(PtrDiffTy);
     llvm::FunctionType *FTy =
       llvm::FunctionType::get(ObjectPtrTy, Args, false);
     return CGM.CreateRuntimeFunction(FTy, "objc_assign_ivar");